Hygrogeus chinensis Cheng & Peng, 2019

Cheng, Zhi-Fei & Peng, Zhong, 2019, A new species of Hygrogeus Mulsant & Rey, 1880 (Coleoptera: Staphylinidae: Omaliinae: Anthophagini) from Xizang, China, Zootaxa 4695 (1), pp. 90-94 : 90-94

Hygrogeus chinensis Cheng & Peng , sp. n.

( Figs 1 A–L, 2A–C)

Type material (2 ♂♂). Holotype: CHINA: ♂ , ‘ China: Xizang A. R., Linzhi City [Ẇźṁ], Motuo Coun. [OiDz º], Mt. West Duoxiongla [MØAELJƜ], alt. 4100 m, 11.VIII.2005, Liang Tang leg. / HOLOTYPE <red rectangular label, printed> ♂, H. chinensis sp. n., det. Cheng & Peng, 2019, SNUC’ (in SNUC) . Paratypes: CHINA: 1 ♂ , ‘ China: Xizang A. R., Linzhi City [Ẇźṁ], Sejila Pass [OEŖLJƜu], alt. 4700m, 2. VIII.2005, Liang Tang leg. / PARATYPE <yellow rectangular, printed> ♂, H. chinensis sp. n., det. Cheng & Peng, 2019, SNUC’ (in SNUC) .

Diagnosis of male. Body black; vertex with deep transverse impression between compound eyes; Maxillary palpomere 3 covered with dense pubescence, significantly shorter than palpomere 4; sternite VII with posteromedian process; aedeagus stout, parameres symmetric, slightly shorter than median lobe, with dense granules and blunt apices, each bearing four long apical setae.

Description. Male, BL 4.81–7.06 mm, FL 3.34–3.61 mm, body ( Fig. 1A ) moderately stout, flattened, covered with fine and dense pubescence and punctures, black, antennae paler, tibiae and tarsi yellowish-brown.

Head ( Figs 1 B–C) subtriangular and transverse, broadest at level of eyes, HL 0.61–0.72 mm, HW 0.89–1.00 mm, HL/HW 0.69–0.72; vertex with deep transverse impression between eyes; frons near each antennal insertion distinctly impressed; clypeus transverse and convex, demarcated from frons by shallow and feeble fronto-clypeal groove; supraanternnal tubercles large and distinctly elevated; compound eyes moderately prominent, about 1.3 times as long as length of temples (holotype); ocelli moderately large and defined, distance between ocelli 0.60 times as long as distance between ocellus and posterior margin of eye (holotype). Punctures on vertex and frons large and distinct, unevenly distributed; pubescence moderately long, sparse and decumbent forwardly; microsculpture distinct, densely distributed. Antennae ( Fig. 1D ) slender, all antennomeres distinctly elongate, relative length of the antennomeres 1–11 (holotype): 0.28 × 0.15: 0.18 × 0.11: 0.21 × 0.11: 0.21 × 0.11: 0.22 × 0.11: 0.22 × 0.11: 0.23 × 0.11: 0.23 × 0.11: 0.22 × 0.11: 0.22 × 0.12: 0.30 × 0.12; AnL 2.43–2.95 mm.

Pronotum subtrapezoidal, distinctly wider than long, broadest near anterior fourth, PL 0.83–0.95 mm, PWb 0.78–1.00 mm, PWm 1.00– 1.17 mm, PL/PWm 0.81–0.83; anterior margin widely rounded, lateral margins arcshaped, basal margin straight; disc moderately convex, with large and shallow posteromedian round impression, and a longitudinal groove along midline from anterior margin to middle. Punctures of disc finer and denser than those of head; pubescence relatively sparse; microsculpture distinct and evenly distributed. Scutellum triangular, with several punctures and pubescence, and dense microsculpture.

Elytra subtrapezoidal, length and width approximately equal, gradually dilated posteriorly, posterior angles broadly rounded, EL 1.67–1.83 mm, EW 1.61–1.72 mm, EL/EW 1.03–1.06; punctures shallower than those of pronotum; pubescence moderately long, denser than those of pronotum; microsculpture lacking. Hind wings fully developed.

Abdomen approximately equal to the width of elytra, widest at segment IV–V, then distinctly narrowing posteriorly. Tergites with dense, fine punctures, distinct microsculpture and decumbent pubescence towards posterior; tergites IV–V each provided with one pair of tomentose admesal patches; tergites VI-VIII with distinct depression near both latus.

Male sternite VII ( Fig. 1J ) strongly transverse, with posteromedian process; sternite VIII ( Fig. 1K ) moderately transverse, apical margin broadly emarginated; apical margin of tergite VIII ( Fig. 1L ) somewhat truncated, indis- tinctly emarginated. Aedeagus ( Figs 2 A–C) stout, AeL 1.34–1.47 mm, in lateral view strongly curved; parameres symmetric, slender, slightly shorter than median lobe, with dense granules and blunt apices, each bearing four long apical setae; median lobe strongly sclerotized, stout, sword-shaped, the lateral margin with deeply rounded emargination near anterior fourth, and stretched shallow emargination near middle; endophallus with two broad sclerites, elongate, fused at basal, and long vas deferens connected to the seminal vesicle, formed annulus.

Female. Unknown.

Comparative notes. The structures of mouthparts, specially maxillary palpi, are unique for this interesting species. Labrum ( Fig. 1E ) subrectangular in dorsal view, with broad emargination anteriorly; covered with dense pubescence. Mandibles ( Figs 1 F–G) subtriangular, each with broad base, and curved distal tooth; left mandible with small basal tooth with two apices, but only with one apex on right mandible; prostheca with short and dense pubescence from base to nearly middle of mandible. Maxillae ( Fig. 1H ) with smooth subtriangular stipes, subrectangular palpifer with long pubescence on external margin, elongate galea with some short pubescence, and slender lacinia with dense pubescence and long teeth. Maxillary palpi elongate, composed of minute and elongate palpomere 1, long and curved palpomere 2 broadening distally, short palpomere 3 with dense pubescence, and long subcylindrical palpomere 4 lacking pubescence. Labium ( Fig. 1I ) elongate, with flattened prementum divided by longitudinal groove anteriorly. Labial palpi bearing several pubescences, palpomere 1, 2 moderately large and elongate; palpomere 3 strongly elongate, distinctly longer than palpomere 2.

By the characteristic shape of the aedeagus, it is similar to H. gulmargensis Coiffait ( India: Kashmir). The new species can be distinguished from H. gulmargensis by stout median lobe, and by the deeply rounded emargination near anterior fourth and stretched shallow emargination near middle at each lateral margin of the median lobe. In H. gulmargensis , the median lobe more slender, and the median lobe lacks distinct deeply rounded emargination and stretched shallow emargination.

Distribution. Southwestern China: Xizang

Etymology. The specific epithet refers to the country where the type locality of the new species lies.

Figures

FIGURE 1. Hygrogeus chinensis, male. Habitus of male in dorsal view (A); head in dorsal (B) and ventral (C) view; right antenna (D); labium in dorsal view (E); right mandible (F) and left mandible (G) in dorsal view; left maxilla in ventral view (H); labrum in ventral view (I); sternite VII (J); sternite VIII (K); tergite VIII (L). Scale bar: 2 mm in A; 1 mm in D; 0.5 mm in B–C; 0.2 mm in H–L; 0.1 mm in E–G.

FIGURE 2. Aedeagus features of Hygrogeus chinensis male. A–C., in dorsal (A), lateral (B), and ventral (C) view. Scale bar: 0.5 mm.